CONTENTS OF No. XV. I. THE WATER SUPPLY OF LONDON, AND THE CHOLERA. By E. Frankland, F.R.S., Professor of Chemistry in III. FOOD AS A MOTIVE POWER. By C. W. Heaton, Professor 7. GEOGRAPHY (including the Proceedings of the Royal Geo London: Manchester: Liverpool: Leeds: Dunkeld. 466 THE QUARTERLY JOURNAL OF SCIENCE. JULY, 1867. I. THE WATER SUPPLY OF LONDON, AND THE CHOLERA. By E. FRANKLAND, F.R.S., Professor of Chemistry in the Royal Institution of Great Britain and in the Royal School of Mines. THE growth of nearly every large town has involved a succession of struggles for the supply of its inhabitants with pure water. Even the aggregation of a few houses forming a village not unfrequently causes a sensible pollution of the water supply, if the wells be sufficiently shallow. As the village develops into a town, the water from such sources not only becomes dangerous from impurity, but also totally insufficient in quantity for the increasing population. Recourse is then had to a neighbouring stream for a purer and more copious supply; but greater abundance of the useful liquid determines the production of a larger volume of sewage, part of which, as the town extends itself along the banks of the stream, begins to be discharged above the point at which the water supply is withdrawn. Contamination again ensues, and the place of withdrawal is removed higher up the river. Relief is thus obtained, but it is only temporary; villages nearer the source of the stream grow into small towns, and the struggle is only terminated by seizing upon and impounding the very sources of the stream itself, by which alone a permanently wholesome and untainted beverage can be secured. Such is the history of water supply in most large towns, and such is, or must be, its history in the English capital. Another visitation of the most terrible epidemic to which modern London is still subject has once more called earnest attention to the serious defects of the metropolitan water supply. It will require much acute observation and laborious experimental research before the origin and spread of cholera will be thoroughly understood; but there are certain prominent features in the character of this epidemic which at once arrest attention and at least suggest the direction in VOL. IV. Y which further inquiry would probably lead to discovery. In the first place we find cholera making its appearance in various localities, healthy or otherwise, and frequently without any apparent cause. Such sporadic attacks occur equally in large towns and in isolated hamlets; as a rule, they carry off the first victim and one or two of his friends or neighbours, whose contact, either direct or indirect, with his dejections can frequently be traced. The disease, however, does not spread farther, but soon becomes extinct, to break out again perhaps in a similar manner after the lapse of weeks or months. In this way, isolated attacks were continually occurring during the summer and autumn of 1866 in Manchester and Birmingham, as well as in scores of small villages and isolated hamlets scattered throughout the whole United Kingdom. Such irregular and sporadic assaults powerfully suggest the presence of a specific poison in the atmosphere suspended as impalpable spores or germs, not therefore obeying the law of the diffusion of gases, but depending upon currents of air for their transport from place to place; in fact, behaving exactly like the spores of green mould or those of the fungus known to gardeners as damp, both of which have so completely taken possession of our atmosphere, that there is probably not a cubic foot of air near the earth's surface which does not contain numbers of them. But these germs, though present everywhere, cannot grow and reproduce themselves except under certain favourable conditions. Place a piece of calf's-foot jelly in a dry atmosphere and it will not become mouldy, but a few hours' sojourn in a damp closet will infallibly cover it with a perfect forest of vegetation. Again, let a geranium be placed in the open air or in a well-ventilated and well-lighted conservatory, and its leaves and stems will continue green and healthy, but let either the light or ventilation be bad, and the plant " damps," that is, it becomes covered with a fungus which rapidly destroys its vitality. Thus both kinds of vegetable spores are incapable of vivification without certain favourable conditions, which are moreover peculiar for each description of organism. The cholera poison, if present in the atmosphere, doubtless also requires a favourable conjunction of conditions to render its development possible. If one of these conditions be absent, the concurrence of all the others is insufficient to produce the effect. Thus, it is highly probable that in the case of cholera, as in that of other epidemic diseases, there are many individuals who, during the time of the epidemic at least, are in such a condition of body as to be absolutely incapable of taking the disease, even if every other favourable circumstance be present. But besides the bodily capacity for the effective reception of the cholera germ, there appears to be in most, probably in all, cases, one other condition at least necessary. This condition may be supplied in food and drink. A young girl in the little village of Farrington, in Lancashire, eats a quarter of a peck of green apples; within twelve hours she is seized with cholera and dies. Another girl does precisely the same thing in Pimlico, and a like result follows. Such are the causes of the socalled sporadic cases of cholera. It is scarcely conceivable that the cholera poison was present in the apples more than in any other article of daily food, but the fruit supplied the only condition wanting to enable the poison to vivify and propagate itself in the system. Now if, during the prevalence of cholera, all the inhabitants of a town, or of one particular quarter of a town, were to eat daily this excessive amount of apples, can it be doubted that the disease would assume what is called its epidemic form, and would attack such of the fruit eaters as were unfortunate enough to be capable of vivifying and propagating the poison? Communities do not, however, thus consume inordinate quantities of apples, or other fruit capable of affording a congenial soil for the cholera germ; but it is evident that if the necessary material were present in bread, milk, butter, or tea, the disease would at once assume its epidemic form throughout the country. Now of all materials which have been observed to determine an attack of cholera there is one which stands pre-eminent. Evidence of the most conclusive character from numerous independent and trustworthy sources points to one material as that best adapted, when introduced into the human stomach, to vivify and develop the cholera germ. This material is sewage. Whether sewage forms a congenial soil for the cholera spores supplied to it from the air or from cholera patients, and thus introduces those spores in an already vivified condition into the stomach, or whether it merely supplies the material for their growth and propagation in the intestines may be disputed, but, divested of all theory whatever, the fact still remains clear and incontrovertible that amongst the materials which, during the prevalence of the disease, produce cholera when taken internally, sewage is the most effective; and this property sewage preserves, although in a diminished degree, even when largely diluted. In the supply of a family with water contaminated with sewage, the necessary condition for the production of sporadic cholera is provided, and in the supply of such a water to a community we furnish the necessary condition for the establishment of epidemic cholera. The history of cholera epidemics furnishes abundant evidence in support of both these propositions; I must content myself, however, by quoting the following cases. On the 18th day of August last a family from London went to reside at Upper Marine Terrace, Margate. On the evening of August 26th a heavy thunderstorm visited the town, and an unusually large quantity of rain fell. The hot water that was brought to the bedrooms the |